Some high-end home entertainment systems have display units (e.g., high definition and/or wide screen display units) having an aspect ratio, horizontal width to vertical height, of 16:9. Video signals (i.e., video, graphical and textual data) received from various sources (e.g., broadcast systems, cable systems, satellite systems, DSL systems and the Internet) have varying aspect ratios. Two such aspect ratios are the 4:3 aspect ratio, often associated with conventional sources of video, and the 16:9 aspect ratio, often associated with sources of high definition video. It is desirable for a high-end home entertainment system having a 16:9 aspect ratio display unit to display video signals having 16:9 aspect ratios as well as video signals having aspect ratios other than 16:9 (e.g., video signals having an aspect ratio of 4:3).
One drawback encountered in displaying a 4:3 video signal on a 16:9 display unit is that the entire 16:9 display is not used to display the 4:3 video signal. This will result in an uneven burn-in of the display unit. In other words, the active video region of the 16:9 display unit will burn-in at a different rate than the non-active regions of the 16:9 display unit. Burn-in relates to the phosphor aging of a CRT screen. All phosphors are subject to aging (browning) such that their light output diminishes with use. As a result, a 16:9 display unit that is also used to display 4:3 video will have significant portions of its phosphor display surface that are not activated in the 4:3 display mode. This will eventually result in a difference in brightness across the display that could be very distracting to a viewer.
One approach to achieve even burn-in is to horizontally expand the active video region over the entire display unit (i.e., expand the 4:3 video signal to 16:9 video signal). However, a drawback to using this approach is that the horizontal expansion leads to an undesirable distortion of the active video. For example, the displayed video may appear horizontally stretched.
Another approach to achieve even burn-in is to horizontally and vertically expand the active video over the entire display unit and maintain the proper proportions of the horizontal and vertical resolutions. However, a drawback to this approach is that some video content (e.g., a sport score located in a corner of the active video) will be moved off screen and will not be viewable by a user.
A further approach to achieve even burn-in is to monitor the illumination of the active video region, calculate an average illumination value, and to display side panels on the inactive portions of the 16:9 display at the average illumination value. The display of the side panels then occurs while the user is viewing the display unit. However, a drawback with this approach is that the user may find the display of the side panels to be distracting when the user is viewing an active video on the display unit. Furthermore, even if the side panels are displayed when the display unit is off, a user who is engaged in an activity in the vicinity of the display unit may find the display of the side panels to be bothersome.
The present invention is directed to overcoming these drawbacks.